STUDIES ON ENZYMES INVOLVED IN THE BIOGENESIS OF LIPID DERIVED VOLATILES IN RIPENING MANGO (MANGIFERA INDICA L.) FRUIT1

Activity of enzymes involved in the biogenesis of lipid-derived volatiles was assayed in five mango cultivars during ripening. Lipase activity was maximum either at harvest maturity and/or at 1/2 ripe stage depending on the cultivar and declined in later ripening stages. Cvs. Banganapalli, Langra and Totapuri had high relative lipase activity. Lipoxygenase activity increased from harvest maturity until 1/2 ripe stage and then declined. The relative activity was maximum in cvs. Langra and Dasheri. Alcohol dehydrogenase activity increased from harvest maturity to either 1/2 ripe stage and/or 3/4 ripe stage depending on the cultivar and then declined. The aldehyde-forming activity was high at harvest maturity, decreased a little in 1/2 ripe stage and thereafter declined rapidly. The cv. Alphonso had higher relative aldehyde forming activity during ripening.     

EMULSION COATING TO EXTEND POSTHARVEST LIFE OF MANGO (MANGIFERA INDICA CV. MANILA)

A coating emulsion was prepared using maltodextrins, carboxymethylcellulose, propileneglycol and a mixture of s orbit an fatty acid esters with an HLB of 6. The emulsion was sprayed on fully mature, unripened manila mangoes, which were the stored at 15 and 25C and 80–85% R.H. At 25C it was observed that rate CO² production increased and lost in control fruits after 12 days of storage. Coated mangoes kept their rate CO² production and suffered only 8% weight loss after 21 days of storage. After storage, the coating was washed out and fruits were allowed to ripen naturally, which occurred in 3–4 days. The results obtained from this study indicate that application of the hydrophobic coating extended the postharvest storage of mangoes for at least 20 days more than uncoated fruits.     

核桃贮藏技术及采后生理研究现状

对国内外核桃贮藏技术及采后生理研究现状进行了综述.同时对核桃贮藏中存在的问题进行了探讨,最后对核桃贮藏保鲜的方向和前景进行了展望.     

CONTROLLED ATMOSPHERE STORAGE of MANGO FRUIT, MANGIFERA INDICA L. cv. RAD

Controlled atmosphere (CA) storage of mango fruit (cv Rad) was studied using two combinations of carbon dioxide (4 and 6%) and three oxygen levels (4, 6 and 8%). the fruits were evaluated at 5 day intervals for various quality attributes, incidence of pathogenic decay and sensory quality. All CA treatments slowed the yellowing of both peel and flesh. After CA storage, fruit were stored at 13, 20 and 30C and the ripening periods were 7, 3 and 2 days, respectively. the best CA storage was 4%CO₂/6%O₂ at 13C.     

PURIFICATION AND PROPERTIES OF POLYPHENOL OXIDASE FROM MANGO PEEL (MANGIFERA INDICA. VAR. RASPURI)

Polyphenol oxidase from the peel of ripe mango fruit (Mangifera indica. Var. Raspuri) was purifed 126-fold to homogeneity by ammoniun sulphate fractionation, column chromatography on Blue Sepharose CL-6B and gel chromatography on Sephadex G-200. It had an iso-electric point (pI) of 4.1±0.2 and molecular weight of 137,000 daltons as determined by sodium dodecyl sulphate—polyacrylamide gel electrophoresis and gel filtration. It was more specific for catechol (than for other substatres tested) with a Km of 8.2 mM. 2-mercaptoethanol, L-cysteine, sodium diethyldithiocarbamate and thiourea were effective inhibitors of this enzyme. It had pH and temperature optima of 5.5 and 46⁰C, respectively. It lost 50% activity by exposure to 85⁰, 75⁰ and 65⁰C for 3, 16 and 25.5 min, respectively. Copper content was one atom per mole of enzyme and copper was essential for its activity. Unlike most of the polyphenol oxidases, multiple forms were not detected in the crude extract.     

PARTIAL PROPERTIES OF POLYPHENOL OXIDASE IN MANGO (MANGIFERA INDICA L. CV. "TAINONG") PULP

The properties of polyphenol oxidase (PPO, EC 1.14.18.1) from an extract of mango pulp were studied. PPO, with catechol as substrate, had an optimum pH at 7.0 and optimum temperature at 30C. PPO showed activity with dihydroxyphenols and trihydroxyphenols, but not with monohydroxyphenols. Kinetic parameters maximum velocity and Michaelis constant for PPO were 256.28 U/min and 6.30 mM with catechol, and 199.61 U/min and 47.81 mM with pyrogallol. The activity of PPO was well retained after heating the extract for 15 min at 50C, and 98% of the activity was lost after the extract was heated for 5 min at 80C. PPO was effectively inhibited by ascorbic acid as well as by β‐mercaptoethanol and L‐cysteine, and was enhanced by sodium dodecyl sulfate.     

NO减压处理对富士苹果采后生理特性的影响

以"富士"苹果为试材,研究了常温贮藏条件下N0(一氧化氮)减压(0.5个大气压,50.662 5 kPa)处理对果实采后生理的影响.结果表明:NO减压处理可延缓果实可溶性固形物的降低;显著抑制果实乙烯释放量,显著降低呼吸强度;减缓果肉硬度下降;显著延缓丙二醛(MDA)含量的升高,从而降低膜脂过氧化程度;提高了POD的活性,减少H2O2的积累.结果表明:适宜浓度NO处理可明显改善其贮藏品质,延缓衰老.     

OPTIMIZING ELECTRON BEAM IRRADIATION OF "TOMMY ATKINS" MANGOES (MANGIFERA INDICA L.)

We determined the optimum irradiation treatment for decontamination of physiologically mature fresh “Tommy Atkins” mangoes, without detriment to the fruits' sensory and chemical properties. Mangoes were irradiated at 1.0, 1.5 and 3.1 kGy using a 10‐MeV linear accelerator (14‐kW LINAC, double beam mode). Mangoes were stored for 21 days at 12C and 62.7% relative humidity with nonirradiated fruits as controls. Dose distribution within the fruit was determined using Monte Carlo techniques. Irradiation did not affect the overall sensory quality of mangoes at doses up to 1.5 kGy. Only fruits irradiated at 3.1 kGy were unacceptable by the panelists. Irradiation at 3.1 kGy enhanced the fruit's aroma characteristics. Irradiation at all levels caused a significant (P ≤ 0.05) decrease (～50–70%) in ascorbic acid content by the end of storage. Mangoes irradiated at 1.5 and 3.1 kGy had slightly higher levels of phenolics than the control (27.4 and 18.3%, respectively). E‐beam irradiation of Tommy Atkins mangoes up to 3.0 kGy causes no detriment to the fruit's overall sensory and chemical quality.     

EVALUATION OF GLOBAL YIELD, COMPOSITION, ANTIOXIDANT ACTIVITY AND COST OF MANUFACTURING OF EXTRACTS FROM LEMON VERBENA (ALOYSIA TRIPHYLLA[L'HÉRIT.] BRITTON) AND MANGO (MANGIFERA INDICA L.) LEAVES

In this work, the global yields, composition and antioxidant activity (AA) of extracts from lemon verbena (Aloysia triphylla) and mango (Mangifera indica) leaves obtained by different separation processes were determined. Lemon verbena extracts were obtained by supercritical fluid extraction (SFE), while mango leaf extracts were obtained by SFE, low‐pressure solvent extraction (LPSE) and hydrodistillation. The extract's constituents were analyzed by thin‐layer chromatography, gas chromatography/mass spectrometry and gas chromatography/flame ionization detector. The AA of the extracts was evaluated by the coupled reaction of β‐carotene/linolenic acid. The cost of manufacturing (COM) was estimated for the SFE extracts. Higher global yields were obtained using SFE at 350 bar/45C (1.49%) for lemon verbena and LPSE (3.04%) for mango. The AAs of the extracts were larger than that of the β‐carotene for both plants. The minimum values of COM were U.S.$26.96 and 52.45/kg of extract for lemon verbena and mango, respectively.     

STORAGE OF IMMATURE GREEN MANGO (Mangifera indica, L.) FRUIT FOR PROCESSING

A suitable method of storing, for processing immature green mangoes in a fresh state was sought. Fruits were stored at three temperatures (1OC, 20C and 30C) either in sealed low density polyethylene (LDPE) bags or paper bags or they were waxed before storage. Storage above 20C proved unsuitable for fruits held longer than one week. Sixty percent of fruits stored at 10C in LDPE bags showed no evidence of pathological infection. Development of severe chilling injury limited the use of waxed and control fruits beyond 14 days at 10C. There were no visible symptoms of chilling injury in fruits stored at 10C in LDPE bags. The majority of fruits stored in LDPE bags at 10C maintained good quality characteristics with acceptable flavor and minimal changes in chemical composition up to 21 days.     

1-MCP处理对"美国8号"苹果采后生理的影响

以“美国8号”苹果为试材，研究了0℃贮藏条件下1-MCP（1-甲基环丙烯）处理对果实采后生理的影响。结果表明：1μL/L1-MCP处理可显著抑制贮藏期间果实乙烯释放量，延缓其跃变高峰的出现，推迟ACO（ACC氧化酶）活性高峰及呼吸跃变峰的出现，抑制采后初期ACO活性及呼吸速率的上升；减缓果肉硬度下降；同时降低脂氧合酶（LOX）活性，并延迟其峰值的出现，延缓了丙二醛（MDA）含量和相对膜透性的升高，从而降低膜脂过氧化程度。结果表明：1-MCP可显著改善其贮藏品质。     

EFFECT OF POSTHARVEST HOT AIR AND FUNGICIDE TREATMENTS ON THE QUALITY OF 'MARADOL' PAPAYA (CARICA PAPAYA L.)

Papaya (Carica papaya L.) fruit is very perishable with a maximum postharvest life of 4 weeks. The effect of forced moist (100% RH) or dry (50%) hot air with or without Thiabendazole (TBZ at 1.2 g active ingredient/L) on the chilling injury (CI), fungi development and quality of ‘Maradol’papaya fruit stored at 5C or 20C for up to 42 days was investigated. Moist hot air at 48.5C or 50C for 4 h caused fruit injury. Dry air at 48.5C for 4 h, alone or in combination with TBZ, decreased CI intensity and fungi development, and the best effect was achieved by combining dry heat treatment and TBZ, without causing negative effects on fruit quality and without causing heat injury. Hot air treatment, especially in combination with TBZ, decreased growth of inoculated Colletotrichum gloeosporioides. Trehalose was not detected in papaya, probably due to the presence of trehalase. Hot water treatment, with or without TBZ, did not cause any negative effect on the content of β-carotene and lycopene.     

THE INFLUENCE OF POSTHARVEST STORAGE, TEMPERATURE AND DURATION ON QUALITY OF COOKED BROCCOLI FLORETS

Fresh broccoli heads (Brassica oleracea L. var, italica) were stored at 1C, 5C or 10C from 0 to 14 days. After this postharvest treatment, heads were cut into florets, which were given a short heat treatment and afterwards stored in plastic bags for a period of 8 days. Storage time and storage temperature before processing affected the texture and color, chlorophyll, vitamin C and β-carotene of cooked florets. The texture of cooked florets was highly correlated with water loss of the raw heads. Significant correlations were found between yellowness, instrumental color measurements and chlorophyll for cooked broccoli. Vitamin C content was affected significantly by subsequent chill temperature storage of cooked florets, which previously were stored at 5C for a period from 0 to 14 days. After 3 or 8 days of subsequent chill temperature storage of cooked broccoli florets, the vitamin C content seemed to reach almost the same level irrespective of the duration of storage of the raw heads, β-carotene content of cooked broccoli florets was stable when raw broccoli heads were stored at 1C and 5C, whereas it decreased towards the end of the storage period when the heads were stored at 10C. After cooking, β-carotene content remained stable during subsequent chill temperature storage.     

STUDIES ON THE EFFECT OF POLLINATION ON THE YIELD AND RESIN CONTENT OF HOPS (HUMULUS LUPULUS L.)

Pollination trials in otherwise male-free hop gardens are described. The results showed that a reduction in cone yield of up to 30% may be expected from seedless hops, but an increase in α-acid content of the cones more or less compensates for this yield reduction and the yield of α-acid per acre can be almost as high from seedless as seeded hops. Northern Brewer, in particular, performed better than other varieties when grown seedless but most of the high α-acid varieties gave reasonable results. It is suggested that the variation in response may depend on the number of resin glands present on the seeds of the different varieties, and differences in the distribution of resin glands on other parts of the cone.